1. Field of the Invention
The present invention relates to a measuring method and device for measuring density as to a gaseous substance and a particulate matter in a gas which is a gas generated in a closed vessel such as a boiler, a refuse incinerator, and a combustion chamber of combustion engine, a gas that is emitted outward from the closed vessel or the emitted gas that is prone to stay around a gas flow stagnation area.
2. Background of the Invention
The methods by use of laser technologies for measuring the density of the gaseous substances and particulate matters in the gas have been conventionally developed whereby the gas is generated in a closed vessel such as a combustion chamber for a boiler, a refuse incinerator, a combustion engine and so on. The gas density measuring technologies by use of laser make use of the property of each kind of gaseous substances; namely, a gaseous substance has the property of absorbing a laser having a component of a wavelength peculiar to the gaseous substance. In other words, the density of a specific gaseous substance is identified by applying a laser including the specific wavelength equivalent to the absorption wavelength peculiar to the gaseous substance toward the measurement object gas containing the gaseous substance, and performing spectrum analysis regarding the laser that passes through the measurement object gas.
It is, hereby, noted that the term “laser” in this specification mainly relates to the lasers that emit a broad spectrum of light, or emit different wavelengths of light simultaneously.
On the other hand, as for the measurement of the density of a particulate matter suspending in the measurement object gas, a method has been conventionally made use of, whereby a predetermined amount of the gas containing the particulate matter is taken as a sample for analysis; the sampled amount of the gas is passed through a filter paper (e.g. a filter paper placed in a cylinder strainer); the difference between the weight of the paper filter after the sampled amount of the gas is passed through the filter paper and the weight of the paper filter before the sampled amount of the gas is passed through the filter paper is estimated so that the particulate matter in the predetermined amount of the sampled gas.
As an example method described above, the patent reference 1 (JP1998-185814) discloses a method for measuring density as to a gaseous substance and a particulate matter by use of the laser technology; namely, the patent reference 1 discloses a density measuring device for simultaneously measuring the densities as to a gaseous substance and a particulate matter, by applying the laser corresponding to the special absorption wavelength peculiar to the gaseous substance, toward the measurement object gas (the gas and the particulate matter therein). In the technology of the patent reference 1, as shown in FIG. 9, the base attenuation Ap regarding the base laser transmittance (transmissivity) corresponds to the attenuation due to the particulate matter; the peak attenuation (absorption) Ag of a sharp valley shape corresponds to the attenuation due to the gaseous substance; thus, the density of the particulate matter can be computed by use of the measured value Ap, while the density of the gaseous substance can be computed by use of the measured value Ag.
Further, the patent reference 2 (JP Patent 3185310) discloses a smoke detector for detecting the smoke emitted from a traveling car (or vehicle); according to the disclosed technology, the to-be-detected smoke may be black smoke, white smoke, water vapor or mixture of white smoke and water vapor; a part of the light (laser) outputted from the laser emitting means is scattered or reflected in the measurement object gas containing the particulate matters; a part of the light is received by a plurality of laser receiving means; according to the light reception conditions of the laser receiving means, the state (such as density information) of the smoke (black smoke, white smoke, water vapor or mixture of white smoke and water vapor) can be estimated.
As described above, the patent reference 1 discloses a density-measuring device that simultaneously measures both densities regarding the gaseous substance and the particulate matter; however, the density regarding the particulate matter is estimated as one overall value; the technology according to the patent reference 1 does not make a distinction among particulate matters in black smoke, white smoke and water vapor; the technology does not reach a level where the density regarding the particulate matter in each smoke can be separately measured. Hereby, it is noted that black smoke, white smoke and water vapor (steam white smoke) mean black smoke containing black solid particulates, white smoke containing liquid particulates and water vapor containing water particulates, respectively.
Further, in the technology according to the patent reference 2, the particulate matter in each smoke such as black smoke, white smoke, or water vapor is measured only independently; the densities regarding the particulate matter and the specific gaseous substance such as NH3 (ammonia) or NOx (nitrogen oxide) in emission gases cannot be simultaneously measured.